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9 votes
3 answers
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How exactly does sensor fusion work in Kalman filters?

I've been looking into implementations of Extended Kalman filters over the past few days and I'm struggling with the concept of "sensor fusion". Take the fusion of a GPS/IMU combination for example, ...
MaskedAfrican's user avatar
4 votes
1 answer
511 views

How to properly initialize every new pose in a Visual SLAM algorithm (namely DSO)?

My question is a bit specific, because it is linked to a certain algorithm. Therefore I didn't find any other solutions on how to go about this problem. If you could refer me to research papers, ...
BlenderEi's user avatar
3 votes
3 answers
168 views

Why Does an Exponential Make ANYTHING a Probability Distribution

I am posting this here because my background in estimation theory and optimization has been developed entirely through my experience in robotics. TLDR: What makes it so that any time you put something ...
JJB_UT's user avatar
  • 120
3 votes
1 answer
58 views

Synthesis gradient observer

I ask the advice of specialists on control systems. We have the following system. Where $u(t)$ and $y(t)$ time-varying input and output. The characteristic $y(t)=f(u(t))$ is assumed to be non-...
ayr's user avatar
  • 183
3 votes
1 answer
307 views

Unstable principal point estimation in zoom camera calibration

I have a camera with a 1/2.9" image sensor from FLIR and a 12-50mm motorized zoom lens from Theia. Because the lens is a motorized zoom lens, I tried to calibrate the camera for different zoom ...
sixer's user avatar
  • 31
2 votes
1 answer
718 views

Visual Odometry terminology: Scale, Relative scale, absolute scale

I'm watching a MOOC about Machine Vision for Robotics, but I really do not know the meaning of some vocabulary of this domain. For example, What does the professor mean when he says this: However, we ...
sci9's user avatar
  • 189
2 votes
2 answers
201 views

How to compute the Hessian matrix in the robustified Gauss-Newton method for optimization

When robustifying the Gauss-Newton method used to find a local minima of a squared error function expressed by: $$f(\mathbf{x})=\frac{1}{2}\Delta\mathbf{z}(\mathbf{x})^T\Delta\mathbf{z}(\mathbf{x})$$, ...
Javier TG's user avatar
  • 123
2 votes
2 answers
435 views

Tracking vehicle 6 states extended kalman filter required?

I'm trying to track an accelerating vehicle using a camera, an IMU, and a GPS. I use for the state space equation a constant acceleration model: The states are the position, the velocity, and the ...
Michael's user avatar
  • 23
2 votes
1 answer
333 views

Applying Rotation & Translation Matrix Obtained from Iterative Closest Point

Suppose I have M lidar contour points from t = k and N lidar contour points from t = k+1. (Some of you might question why I have differing number of contour points, and the reason is that these lidar ...
Dong Jae Lee's user avatar
2 votes
2 answers
502 views

How do you handle angle discontinuities in estimation problems?

When one is implementing a state estimator in a system that involves kinematics, will inevitably face the problem of angle discontinuities, i.e., the fact that the angles have to be wrapped between ...
D Dim's user avatar
  • 21
2 votes
1 answer
93 views

Methods for state estimation and real-time path planning of a mobile robot

I'm looking to start a project that incorporates some form of state estimation and path planning for a simple simulated robot dynamic model, in an environment that contains obstacles. I'm hoping to ...
InquisitiveInquirer's user avatar
2 votes
1 answer
327 views

Particle Filter for IMU tilt angle and bias estimation from Kalman Filter models

I understand the functioning of Particle Filters from the book Probabilistic Robotics and the robotics course provided by Cyrill Stachniss. I want to implement, from scratch, a particle filter to ...
Shrinivas Iyengar's user avatar
2 votes
0 answers
133 views

Wheeled Mobile Robot State Estimation Model Using Odometry

I have a process model update that follows the form: $$ \mathbf{x}_{k|k-1} = \mathbf{x}_{k-1|k-1} + \delta \mathbf{x}_k, $$ where $\mathbf{x}_{k-1|k-1}$ is the posterior estimate from the last ...
joe.dinius's user avatar
1 vote
2 answers
338 views

Is Luenberger observer applicable in practical systems?

I have tried to find out about this from quite a few sources but it still remains unclear to me. I know that the Luenberger observer is applicable for a deterministic system with known control inputs ...
OrangeDurito's user avatar
1 vote
1 answer
786 views

Obtaining Heading vector from IMU

First time here. I'm an electronics engineer who has been tasked with this problem: Given the 4D quaternion representing a vehicle orientation, how do you get the heading vector? The vehicle ...
Pioneer83's user avatar
  • 111
1 vote
1 answer
119 views

Reset coordinate system of robot while maintaining relationship to the previous

I am currently estimating a robot's pose (3d position and rotation matrix) with an IMU and I want to reset the localizer in the middle of the run while keeping the relationship to the pose it had when ...
Damuno's user avatar
  • 11
1 vote
1 answer
608 views

The biases in the state vector of Extended Kalman Filter(EKF)

I am reading one paper on observability Observability Analysis of Aided INS with Heterogeneous Features of Points, Lines and Planes. The state vector contains the current IMU state and the feature ...
Jogging Song's user avatar
1 vote
0 answers
17 views

Propagation of covariance matrix during a rotation

Suppose we have a rotation matrix representing an objects rotation in a certain frame $F_1$ along with a distribution of Euler Angles representing the probability that the object is perturbed from ...
FourierFlux's user avatar
1 vote
0 answers
30 views

Observability of Gravity in SLAM

A number of SLAM systems only optimize over 4 variables(location and yaw) as they argue gravity is observable which constrains roll and pitch. I don't understand this argument since in theory you ...
FourierFlux's user avatar
1 vote
1 answer
62 views

Covariance of fused poses. Should it be normalised by the number of poses?

I came across this paper from T. Barfoot and P. Furgale: "Associating Uncertainty With Three-Dimensional Poses for Use in Estimation Problems" Link: http://ncfrn.mcgill.ca/members/pubs/...
mcamurri's user avatar
0 votes
1 answer
62 views

Rotation of a point in 3D space

I want to rotate a point (3,4,5) by an angle 45 degrees(0.785398 rad) in 3D space. I have used the standard DCM matrix in the order Rx, Ry and Rz. Where, theta = 0.785398, Rx= ( [ 1, 0, 0] [ 0, cos(...
Tanvi Sawant's user avatar
0 votes
1 answer
65 views

wheeled vehicle forward velocity from RPM brushless data

I'm trying to hack an electric RC car with the goal to make it autonomous, as part of my PhD research. The mounted ESC is able to send back telemetry data, including the spinning velocity (in RPM) of ...
Maik93's user avatar
  • 103
0 votes
1 answer
118 views

Kalman Filter Design

I'm new to Kalman filter design and I'm struggling to understand how to apply the Kalman filter methodology to my problem. I've read a research paper which seems to describe what I'm trying to do ...
Joe's user avatar
  • 69
0 votes
1 answer
505 views

Is the covariance matrix in the extended Kalman filter guaranteed to be positive definite (ignoring numerical errors)?

I understand that due to numerical errors (e.g., round off error and machine precision) that the covariance matrix may not be positive definite, but if computers had infinite precision, is the ...
Ralff's user avatar
  • 345
0 votes
2 answers
62 views

How do I get competent in using c++ for my projects? [closed]

I am a PhD student, working on Sensor Fusion and estimation problems. I would like as I finish my PhD to have acquired sound knowledge in what seems to be the industry norm for working with real ...
D Dim's user avatar
  • 21
0 votes
1 answer
232 views

Advantage of Kalman filter in differential drive planar robot

We need to estimate the position and orientation of differential drive robot by using encoders and imu sensor. For this specific case, is there any advantage of using Kalman filter than taking the ...
Pasha's user avatar
  • 149
0 votes
1 answer
93 views

UKF for a serie of observations with covariance

I have some doubts about how to implement a UKF-like algorithm when I only have motion observations and no control inputs. Assume I have a robot with state $s_t = (x_t, y_t, \theta_t)$ and the ...
Federico Taschin's user avatar
0 votes
2 answers
85 views

Is this encoder error expected?

I'm working with the iRobot Create 2. When I read the encoder count and sum it for total, I'm able to do so without apparent error. I've used this to 'successfully' estimate position combining with ...
Stephen Taylor's user avatar
0 votes
1 answer
431 views

Estimate noise covariance matrix of measurements using a ros-bag

I am facing the following issue, and some hint or orientation would be great. I am working on a project in which I was given a ROS bag, and I have to implement a localization node using SLAM. To do so,...
adiego73's user avatar
0 votes
1 answer
436 views

Fusing IMU sensor with odometry

Would fusing Odometry estimation with IMU sensor increase the accuracy of estimation for planar differential drive robots?
Pasha's user avatar
  • 149
0 votes
1 answer
4k views

Orientation from magnetometer data

I saw lot of topics with the same title but answers are different. I have a magnetometer in my phone which give me the components of magnetic field in direction of X, Y, Z. If my phone lays on a ...
Robert's user avatar
  • 1
0 votes
1 answer
364 views

How can I compute the covariance of a camera-based relative pose measurement?

I am trying to compute the relative pose between two cameras using their captured images through the usual way of feature correspondences. I use these feature matches to compute the essential matrix, ...
HighVoltage's user avatar
  • 1,106
0 votes
0 answers
4 views

Confusion on optimizing variable time-offset for VIO SLAM

I was reading the following paper on how you can incorporate variable time offset for a camera in VIO: https://openaccess.thecvf.com/content_ECCV_2018/papers/Yonggen_Ling_Modeling_Varying_Camera-...
FourierFlux's user avatar
0 votes
0 answers
11 views

Is it possible to do uncertainty propagation with TF2? If not what can I use?

I'm interested in applying a sequence of linear transformations to a gaussian probability vector in TF2. As far as I understand this is a pretty operation due to the gaussian nature and I see TF2 has ...
FourierFlux's user avatar
0 votes
0 answers
13 views

How to transform the detected target pose into the pose in the camera coordinate system in Gazebo

that is my code ...
chan mlen's user avatar
0 votes
0 answers
37 views

What are some resources to learn Probability, Statistics and Stochastic Processes so I can understand Optimal State Estimation?

I went to grad school for Mechanical Engineering almost 7 years ago, where I avoided any probability/stats coursework like plague and stuck to linear algebra and differential equations for my math ...
ICRed's user avatar
  • 1
0 votes
0 answers
22 views

Does the Factored Quaternion Algorithm Account for Declination?

Looking at the documentation for the Factored Quaternion Algorithm (FQA). In section 2 they define NED as the traditional Earth's fixed coordinate system, thereby referring to 'true' north. However, ...
sbourne's user avatar
0 votes
1 answer
2 views

Accessing previous estimated joint states of a robot

Hi, I am new to ROS and I am trying to implement a Kalman filter for estimating the joints velocity and acceleration of a robotic manipulator. The angular position of each joint is published to the ...
user avatar
0 votes
1 answer
6 views

find position of object in a bag

Hi guys, I need to find(estimate) the 3D position of the 'people in the scene' -- (this is in the bag file) with respect to the camera. My code is : (I didn't write it) ...
user avatar
0 votes
1 answer
1 view

Zigzag ground track from eight shape flight path

Hi all, I tried to using ukf template recursively with navsat_transform node following http://answers.ros.org/question/200071/how-to-fuse-imu-gps-using-robot_localization/ With my eight flight path it ...
user avatar
0 votes
1 answer
36 views

amcl restore own position automatically

sometime AMCL can't localize itself in the given map while moving. such as in alike environments. In similar cases I use pose estimation button for real position of robot. But is there a way to detect ...
user avatar
0 votes
1 answer
3 views

Multiple static target position estimate

An aerial vehicle captures images of the ground, using a down facing camera, in order to detect some static ground targets. Using opencv I created a node that detects those targets and converts their ...
user avatar
0 votes
1 answer
25 views

amcl estimation quality

I would like to know how much to trust the amcl output pose. One thought is to see how well the laser data correlates with obstacles in the cost map, another is to calculate the variance of the ...
user avatar
0 votes
1 answer
5 views

AMCL parameters spreading out is good or bad?

hello... I cant understand , How do I decide whether the amcl parameters result is good. so AMCL Pose estimations spreading out is good or bad ? which image is good result ? this my new amcl ...
user avatar
0 votes
2 answers
21 views

State Estimation and Localization in Robot Navigation

Hello, I would like to ask the difference between a state estimator like robot_localization, or robot_pose_ekf and a ...
user avatar
0 votes
1 answer
15 views

ROS Answers SE migration: robot pose ekf

Hi all, i'm trying to make this node run just with my IMU Microstrain 3DM-GX3-25. For this I use the node provided here. If I run them as they are the IMU is outputting the data correctly, while the ...
user avatar
0 votes
1 answer
1 view

robot motion estimation

Hello I have some problems with my amcl , the motion estimation and the calculated linear and angular velocity. My robot is an electrical wheelchair with camera, laser range finder and IMU. For the ...
user avatar
0 votes
0 answers
275 views

Estimating gyroscope bias for attitude IMU sensor fusion with an unscented Kalman filter

I'm trying to use a UKF as the attitude estimator for a drone with just a gyroscope and accelerometer as sensors. So far, it's going well and after some tuning appears to perform basically as well as ...
brennanenanen's user avatar
0 votes
0 answers
79 views

EKF Update Step measurement data doesnt fit state vector

I have an EKF SLAM Algorithm which tries to estimate the robots position (X,Y,Theta) + the X,Y coordinates of several landmarks. Like in the posted algorithm i have a range/bearing sensor. I ...
muller135's user avatar
0 votes
0 answers
62 views

Differences between strapdown inertial navigation and motion models

In a state estimation scheme with a simple IMU/GNSS setup using EKF, I have always thought the prediction step would be done using a motion model and all sensor measurements would be incorporated via ...
vasf's user avatar
  • 1